A known example of the abovementioned indirectly heated electrode for gas discharge tube is that which is disclosed in Japanese Examined Patent Publication No. 62-56628 (U.S. Pat. No. 4,441,048). The indirectly heated electrode for gas discharge tube (indirectly heated cathode for gas discharge tube) that is disclosed in Japanese Examined Patent Publication No. 62-56628 has an arrangement wherein a double coil is wound a plurality of turns around and fixed closely to the outer wall of a cylinder of good thermal conductivity, a uniform cathode surface is formed by applying a paste-form cathode material in the space inside the primary coil and between the secondary coil of the double coil, and providing a heater inside the cylinder.